Radar bands explained: X, K, Ka, Ku and laser
Last updated August 2026 · McFlash editorial team
Every detector spec sheet lists bands. Only two of them decide whether the device is useful on US roads today: Ka and K.
The bands, one by one
| Band | Frequency | What it means for you |
|---|---|---|
| X-band | 10.5 GHz | Rare in US enforcement today. Still used in a few eastern states and by some automatic door sensors, so X alerts are usually false. |
| K-band | 24.15 GHz | Widely used by state and local police. Also the band used by blind-spot monitors and door openers — the main source of false alerts. |
| Ka-band | 33.4–36.0 GHz | The dominant modern enforcement band in the US. Ka sensitivity is the single most important spec on any detector. |
| Ku-band | 13.45 GHz | Used in Europe, effectively absent from US roads. Harmless to have. |
| Laser (LiDAR) | 904 nm infrared | Not radio at all. Very narrow beam, so an alert usually means you were already targeted. |
| VG-2 / Spectre | — | Radar-detector detectors used by enforcement in ban jurisdictions. Relevant only where detectors are illegal. |
How to read an alert in real traffic
A Ka alert that strengthens steadily as you drive is almost always genuine enforcement — slow down. A K alert that spikes hard and vanishes within a second or two as you pass a storefront or another car is nearly always a door sensor or a blind-spot monitor. An X-band alert in most of the country is noise.
This is why band callouts matter more than a single beep. McFlash announces the band aloud, so you can judge an alert without taking your eyes off the road. See the specs.
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